Inhalation nebulizers deliver therapeutically effective amounts of pharmaceuticals by forming an aerosol which includes particles of a size that can easily be inhaled. The aerosol can be used, for example, by a patient within the bounds of an inhalation therapy, whereby the therapeutically effective pharmaceutical or drug reaches the patient's respiratory tract upon inhalation.
A variety of inhalation nebulizers are known. EP 0 170 715 A1 uses a compressed gas flow to form an aerosol. A nozzle is arranged as an aerosol generator in an atomizer chamber of the inhalation nebulizer and has two suction ducts arranged adjacent a compressed-gas channel. When compressed air flows through the compressed-gas channel, the liquid to be nebulized is drawn in through the suction ducts from a liquid storage container.
This nebulizer is representative of continuously operating inhalation nebulizers, in which the aerosol generator produces an aerosol not only during inhalation but also while the patient exhales. This is represented schematically in FIG. 1A, in which a respiration cycle consisting of an inhalation phase and an exhalation phase is shown. The aerosol produced by the aerosol generator is actually inhaled by the patient only in the inhalation phase, while any aerosol produced at other times is lost.
In order to avoid aerosol losses, attempts have been made to restrict aerosol production to part or all of the inhalation phase, thereby obtaining the course schematically represented in FIG. 1B. Either a patient can interrupt aerosol production manually, or the patient's respiration can be detected by sensors that automatically control aerosol production. Neither situation is flawless, as manual control of aerosol production is an additional strain for patients and often leads to insufficient results. Automatic control of aerosol production represents an enormous technical expenditure which as a rule bears little relation to the obtained benefit.
Thus, a need remains for an inhalation nebulizer by means of which, with a low constructional expenditure, an increased amount of aerosol can be provided in the inhalation phase, while at the same time the aerosol losses during the exhalation phase can be reduced.